The present invention relates to improvements in plastic reclosable fasteners or zippers with sliders for opening and closing the zippers on plastic-film bags and the like and particularly to a provision of a leakproof plastic zipper with integrated end stops for the zipper slider at the ends of the plastic zipper to seal the ends of the zipper and to provide stops to retain the slider on the zipper.
Plastic reclosable fasteners or zippers with sliders are well known in the art. The plastic zippers include a pair of male and female fastener elements in the form of reclosable interlocking rib and groove profile elements for cooperation with the slider for opening and closing the rib and groove elements. In the manufacture of plastic-film bags, a pair of these male and female profile elements extend along the mouth of the bag and are secured in any suitable manner to the flexible walls of the plastic-film bag. These zipper elements may be integral marginal portions of such walls or they may be extruded separately and thereafter attached to the walls along the mouth of the bag.
Various arrangements have been utilized heretofore to provide a leakproof plastic zipper and to prevent the slider from sliding off the end of the zipper. One arrangement is disclosed in U.S. Pat. No. 3,259,951--Zimmerman. In this patent, opposing interlocking or mating strips are permanently joined or sealed to each other at the ends with a separate stop member sealed between these members to stop the longitudinal movement of the slider therealong. The strips are notched at one end to receive the separating member of the slider. Another leakproof zipper with slider is disclosed in U.S. Pat. No. 5,020,194--Herrington et al. In this patent, the zipper structure is slit or notched locally at the end where the slider goes when the zipper is closed to allow the rib and groove elements to interlock fully making a leakproof closure. The U.S. Pat. No. 5,088,971--Herrington and U.S. Pat. No. 5,131,121--Herrington et al disclose end stops that are created from existing material of the profile rib and groove elements at the opposite ends of the zipper, and that protrude transversely from the zipper a distance adequate to engage the sides of the slider and thus prevent movement of the slider past the respective ends of the bag. In U.S. Pat. No. 5,161,286--Herrington et al end clamps are located at the opposite ends of the zipper. A pair of end clamp members is connected together by a flexible strap which extends over the top of the zipper and by a rivet that extends through the pair of end clamp members and the sidewalls of the bag below the profile rib and groove elements of the zipper to secure the end clamp members to the bag. In U.S. Pat. No. 5,067,208--Herrington et al the plastic reclosable fastener and slider include end clamp members and a provision for restraining the slider in closed position and maintaining the male and female elements of the fastener in interlocking relation when the slider reaches the closed end of its travel along the tracks of the slider.
It would be desirable to provide a leakproof plastic zipper with integrated end stops for the zipper slider wherein the volume of material available at the ends of the rib and groove elements is not only adequate for forming integrated end stops without the need for end clamp members but is also adequate to include window structure for receiving the separator finger on the slider thus allowing the interlocking elements to close completely beneath the slider and create a leakproof seal. It would also be desirable to have the window create a "detent" effect in the closed position to maintain the slider in the closed position.